This invention relates to cathode ray tube meters which provide visual representations of signal levels in plural signal channels. The invention relates, more particularly, to cathode ray tube meters which provide a plurality of visible, vertical traces on the screen of an oscilloscope, the length of each respective visible vertical trace representing signal level in an individual one of the signal channels.
It is often desirable to monitor the signal levels of a number of signal channels, particularly in multi-channel sound recording systems, multi-channel broadcast systems and, to a lesser extent, in multi-channel playback systems.
In most broadcast and sound recording studios, VU meters are used to set peak signal levels on lines which feed a broadcast transmitter, signal mixer or recorder. The conventional VU meters most often involve appropriately damped meter movements of the electromagnetic deflection type. The needle of the meter movement is deflected in proportion to the signal level. One meter must be provided for each channel in the event more than one channel is to be monitored simultaneously at any given time. In some instances, one conventional VU meter having an associated manually operated, selector switch may be provided, the position of the switch determining which channel is being monitored at any given time.
Arrangements of the type described above have a number of disadvantages. The size of the meter faces is such that it is difficult for a person monitoring a number of signal channels to have a good view of all meter faces at once. The meter movements often are not capable of following fast changes in signal level, due to the mechanical inertia of their moving parts.